I've never had a problem with my front windows down and my dogs. Sure it's a little chilly but that's what a jacket is for.

FWIW I see people close the tailgate first and set the hardtop window on the tire and drive like that. If you're driving freeway I'd secure it and I'd stay out of a lot of stop and go traffic too if its avoidable, but I know it isn't lol

I have only had mine open while driving about three times. I didn't really notice the fumes. I had the fronts open too. I had it open while moving a coffee table. I dunno, didn't break and I'm still breathing. I think with the gas shocks in working order, it dampens the bumps.